Vindex adn Probit are the flagships. I would advise you to get involved. But I would not invest a very large amount of money. Try to buy $ 100. You will not lose much and if successful you will get a big profit. Many say that Vindax has been experiencing problems lately but such problems are solvable once this project was able to afford IEO on Binance.
Probit is an average crypto exchange. But they have listed some projects on their IEO launchpad which has scam accusation in Bitcointalk forum! And, I don't agree that Vindax is a flagship exchange. VindaX and Latoken and Exmarkets all are similar types of exchanges, not good enough for investment, all of their IEO projects not good enough.
All of the exchanges that you mentioned are very sad because these exchanges do a lot of IEO but the Projeck that they issue does not provide benefits. instead, investors are harmed by fictitious projects that are deliberately made. we should all be aware to avoid these projects because they are clearly detrimental